The invention relates to friction heat generators of the type having stationary and rotatable friction discs with a thin fluid film between the discs. Disc interface pressure is created perpendicular to the disc surfaces, and heat is generated by the shearing of the thin fluid film.
The quantity of heat generated in a friction heat generator is dependent, in part, on the total surface area of the thin fluid film, the rotational velocity of the moving discs in relation to the stationary discs, and the disc interface pressure. The quantity of heat generated increases as each of these variables increase. Heat transfer fluid is provided to pick up heat while flowing through heating chambers located within each disc.
Friction heat generators are well known. It has been found that such friction heat generators as heretofore constructed generally operate with a constant predetermined value of interface pressure between the friction discs. In one prior art device, the disc interface pressure is changed only by manual adjustment of a spring. This adjustment, however, is generally not made while the generator is operating.
At any given disc interface pressure, the generator's running torque is relatively constant, and the quantity of heat produced in a given period of time is dependent on a single function: that being the rotational velocity of the disc assemblies. Such heat generators operate with either low starting and running torque and consequently relatively low quantity of heat output even when high power input is available; or higher starting and running torque and no useful heat output when only low levels of power input are available. These characteristics of the heat generator do not permit high efficiency operation over a broad range of power input.
Regardless of whether prior friction heating generators operated with low or high starting and running torque, these prior devices had no alternative provisions for the use of driving power at levels below that required to generate a useful quantity of heat output. For instance, one of these prior friction heat generators could be driven by a windmill or other variable power source. On a day with only a light wind, the windmill would not supply enough power to overcome the starting or running torque and therefore no heat would be generated. The wind power, from such light wind would be lost.
It would be advantageous to provide an auxiliary apparatus to store the energy from a light wind, and then to release it back into the friction heat generator system at a time when a stronger wind was blowing.
Another disadvantage of friction heating generators, as heretofore constructed, is that they permit a significant volume of the circulating heat transfer fluid to bypass some of the friction disc assemblies without ever passing through or near heat producing surfaces. The fluid, therefore, is heated only indirectly by mixing with the high temperature fluid discharged from the heating chambers.
Additionally, in the older devices, loss of fluid in the generator for any reason results in very rapid heating of the discs and potentially serious damage to them unless the driving power to the generator is withdrawn almost immediately.
Prior friction heating generators had no means to automatically increase the flow of heat transfer fluid as the quantity of heat generated increases.
It would therefore be advantageous to provide means for automatically increasing the flow of heat transfer fluid through the heat generator, as the heat output of the generator is increasing.
It would also be advantageous to provide means for automatically increasing the friction disc interface pressure, as the driving power input to the generator is increasing.